A popular type of electrical connector which is used widely in the electronic industry is called an "edge card" connector. An edge card connector receives a printed circuit board or card having a mating edge and a plurality of contact pads adjacent the edge. Such edge card connectors have an elongate housing defining an elongate receptacle or slot for receiving the mating edge of the printed circuit board. A plurality of terminals are spaced along one or both sides of the slot for engaging the contact pads adjacent the mating edge of the board. In most applications, such edge connectors are mounted on a second printed circuit board. The mating edge board or card commonly is called the "daughter" board, and the board to which the connector is mounted commonly is called the "mother" board, a backplane or a base board.
One of the problems with edge card connectors of the character described above centers around the ever-increasing demands for high speed and miniaturized electronic circuitry. The terminals of such a connector are mounted in a housing fabricated of dielectric material such as plastic or the like. Not only are the terminals becoming ever-increasingly miniaturized, but their density within the housing is becoming greater and greater. The terminals are mounted in rows along the slot of the housing with the terminals being separated by dielectric partitions or walls integral with the housing, and the housing includes side walls for surrounding the terminals. Unfortunately, such high density circuitry can result in increased crosstalk and poor impedance control.
For example, microprocessors operate at ever increasing frequencies and communicate with ancillary devices such as memory, display drivers and the like over wide channels with increasing numbers of parallel connections. The interconnection of such high frequency circuitry may be accomplished with connectors having closely spaced terminals, terminals having relatively small cross sectional areas, or both. The requirement for high frequency operation results in the need for a controlled impedance in order to transmit or pass fast digital pulse rise times with minimal distortion. However, close circuit spacing can result in the aforementioned increased crosstalk due to signal-to-signal coupling. The present invention is directed to solving this myriad of problems and particularly to providing a terminal arrangement wherein the signal terminals are provided with controlled signal-to-ground capacitive coupling and shielding along substantially the entire signal paths of the terminals and therefore resulting in controlled inductance and impedance.